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NAV2

#nav   #slam  

Table of Content

Coordinate frames#

  • base_link
  • odom: world origin
  • map
  • base_footprint: like base_link but keep in 2D

Note

Measure robot velocity
Velocity integrated to estimate position (dead reckoning)

TF’s#

odom: Odometry Origin map: World origin

Topics#

/odom: nav_msgs/msg/Odometry /map: nav_msgs/msg/OccupancyGrid

install#

sudo apt install ros-humble-slam-toolbox
sudo apt install ros-humble-navigation2
sudo apt install ros-humble-nav2-bringup

slam-toolbox#

Online: Working in a live data (not recorded) Asynchronous: Always process the most recent scan , avoid lagging (skip scan if lagging)

ros2 launch slam_toolbox online_async_launch.py params_file:=./src/basic_mobile_robot/config/slam_async.yaml use_sim_time:=true

  • Save map: Old format, create pgm and yaml files
  • Serialize map: New format , create posegraph and data file

slam_toolbox high cpu

change param do_loop_closing to false

AMCL#

map server#

ros2 run \
nav2_map_server \
map_server --ros-args \
-p yaml_filename:=my_map.yaml 
-p use_sim_time:=true

# Activate
ros2 run nav2_util \
lifecycle_bringup map_server

# test
ros2 service call /map_server/load_map nav2_msgs/srv/LoadMap "{map_url: /home/user/nav2_ws/new_map2.yaml }"

amcl#

ros2 run nav2_amcl amcl --ros-args -p use_sim_time:=true

# Activate
ros2 run nav2_util lifecycle_bringup amcl

[WARN] [1676219701.288565313] [amcl]: AMCL cannot publish a pose or update the transform. Please set the initial pose...

launch file#

map server#

Node(
    package='nav2_map_server',
    executable='map_server',
    name='map_server',
    output='screen',
    parameters=[
        {'use_sim_time': True},
        {'yaml_filename':map_file}]
    )

lifecycle_manager#

Node(
    package='nav2_lifecycle_manager',
    executable='lifecycle_manager',
    name='lifecycle_manager',
    output='screen',
    parameters=[
        {'autostart': True},
        {'node_names': [
            'map_server',
            'amcl']
        }
    ]
)

Reference#